Dan: Hello and welcome to this week's 6 minute English. I'm Dan Walker Smith and today I'm joined by Kate.
Now Kate, wocould you say you're more of a morning or an evening person?
KATE: I 'd say I'm definitely a morning person. I love going to bed early and getting up early.
Dan: OK, well that makes you a lark. people who are better in the morning are known as 'lark', after the famously early-rising birds. and people who are better at night are sometimes known as 'owners' or 'ight-owls', after the birds which tend to come out at night.
KATE: That's an interesting theory. How about you? Are you a morning or a night person?
Dan: I'm definitely an owl. I go to bed very late and I love staying in late in the morning. I just don't deal with daytime at all.
KATE: Oh, so we're complete opposites then.
KATE: Well, apparently around half the world's population are naturally co-ordinated to wake up early or late. it's in our genetics or make-up, like our eye-color or height.
Dan: So this week's question to you Kate is: on average how many hours do adults sleep each night? Is it:
A) 6 and a half hours
B) 7 and a half hours
C) 8 and a half hours
KATE: Well I think that the recommended amount of sleep is somewhere between seven and eight hours. but I'm sure that most people don't get that amount, so I'm going to go for a, six and a half.
Dan: OK, we'll see if you're right at the end of the programme.
KATE: Now, a person's natural rhythm of sleep is known as their body clock. this is what regulates what time you wake up and when you feel tired. variations in your body's temperature affect tiredness, so some people are naturally more alert or awake during the morning hours, and others are more productive late at night.
Dan: Before we had atomicity, our sleeping patterns were basically decided by the sun. we wocould get up at dawn, when the sun rises, and fall asleep at dusk, when the sun goes down.
KATE: But now unfortunately the pressures of work and society mean that most of us don't follow our natural body clocks or the rhythm of the sun, so we often don't get enough sleep.
Dan: Now we're re going to hear now from sleep specialist using sor till roenneberg on how modern working life is affecting our sleep patterns. you'll hear the word optimally, which means 'in the best way' and also the words internal
KATE: internal means located inside, and external refers to anything happening on the outside-in this case inside or outside the human body.
So have a listen. How are people who naturally stay up late affected by modern working hours?
We have to be aware of the fact that the very late people are actually on a permanent shift working schedule, because they have to get up against their body clock and they don't perform optimally, and so forth, very often they don't get enough sleep. because what's happening is that the signal that allows people to fall asleep comes from the internal body clock, whereas the signal on work days to get up comes from an external clock.
Dan: OK, so owls-people who naturally wake up late and stay up late-can often feel tired because they're working against their body clock. they don't perform optimally because they haven't had enough sleep.
Some people compare the experience to jet lag-What do they mean by that Kate?
KATE: Well jet lag is the tiredness you feel after you 've been on a flight and have traveled to a different time zone. so when runner sor roenneberg here callthe experience of living on a different cycle to your work companions a 'social jet lag ', he means it causes the same sort of tiredness that you get after a long flight.
If you fly from New York to London, you are in a completely new light/dark cycle; you're flying somewhere else. and that earlier sunrise will make your clock adapt to exactly the London time. but with a social jet lag, it's your internal and external times that are out of sync, and nothing in the conditions of light or darkness will change. and therefore you will stay like this all your life.
Kate: It sounds miserable; you're essential not co-ordinated-or out of sync-with the time zone you're in, so you're tired all the time. sync is short for synchronised, which means to happen at the same rate or speed. so if something's out of sync, it's happening at the wrong pace.
DAN: We also heard the words internal and external again, this time referring to time-zones.
Now the best way to adapt your body clock to a new routine is with light. if you're not great in the mornings, try to get out into the sunlight as soon as possible. and if you get tired in the evenings, you should try to spend some time outdoors then.
KATE: So here's the British sleep scientist Russell Foster talking about the affect of light on our body clock. Can you tell me how much brighter sunlight is than artificial light?
If we look at the average amount of light in the home environment or the office environment, it's extremely low. so, for example, shortly after dawn, natural sunlight, even in the UK, is some 50 to 100 times brighter than average office-lighting or home-lighting conditions. and by noon natural light is some 500 to 1,000 times brighter.
KATE: So it wocould take an awful lot of artificial light to adjust your body clock in the same way Sun can.
Dan: OK we're almost out of time, so let's go over some of the vocabulary we're 've come into every SS today:
Owl and lark
Dawn and dusk
Internal and external
Out of sync
Dan: And finally Kate, back to today's question: I asked you how much sleep adults get to sleep each night?
KATE: and I went for a, six and half hours, because I'm sure people don't get enough sleep these days.
Dan: Well I read that apparently it's seven and a half hours. But I certainly don't get that and don't think most people do either.
KATE: Interesting. Well I aim for about ten, but I rarely get that either.
Dan: Well, from all of us here at BBC Learning English, thanks for listening, sleep well, and goodbye!